System for recovering and utilizing waste heat



July 16, 1940. F. P. GRUTZNER SYSTEM FOR RECOVERING AND UTILIZING WASTEHEAT Filed July 51, 1937 3 Sheets-Sheet 1 FIG.1.

INVENTOR.

BY FRITZ PAUL GRUTZNER ATTORNEY.

July 16, 1940.

F. P. GRUTZNER SYSTEM FOR REGOVERING AND UTILIZING WASTE HEAT Filed July31, 1937 47' FIG. 2.

3 Sheets-Sheet 2 INVENTOR.

FRITZ PAUL GRUTZNER ATTORNEY.

Juiy I6, 1940.. F. P. GRUTZNER 2,208,157

SYSTEM FOR RECOVERING AND UTILIZING WASTE HEAT Filed July 31, 1937 3Sheets-Sheet 5 FIG. 3.

INVENTOR.

F RITZ PAUL GRUTZNER BY @LW ATTORNEY.

Patented July 16, 1940 UNITED STATES SYSTEM FOR BECOVERING ANDUI'IIJZING WASTE HEAT Fritz Paul Grutmcr, Beloit, Wis, asaignor toFairbanks, Morse a 00., Chicago, 111., a corporation of IllinoisApplication July 31, 1937, serial No. 156,852

11 Claims. (01. 2a7- -1z.1)

This invention relates to systems for recovering and utilizing wasteheat from internal combus-- tion engines, and more particularly toimproved methods of and means for recovering and utiliz- 5 ing heat fromthe exhaust discharge, and cooling system of an internal combustionengine.

This invention is well adapted for application in buildings, ships, andsimilar structures where there is a demand for power, space heatingandhot service water. The subject matter of this application is acontinuation in part of my copending application for Heating andventilating systems, bearing Serial No. 85,272, filed June 15, 1936.

1a In accordance with the foregoing, the principal purpose of theinvention is to provide a system for recovering waste heat produced inthe operation of an internal combustion engine and for utilizing theheat recovered, as for the heating of service water.

Among other objects may be noted the provision of a system which ispositive and automatic in its function to attain the purposes of theforegoing object, and one which is operable independently of powerdemands on the engine; the

system including, also, mechanism of thermostatically controlled type,operable to regulate the temperature of the engine jacket water and thatof the hot service water, particularly with respect to maximumtemperature limits thereof.

A further object is to provide a system for the purpose described, inwhich the elements comprising the systemare so arranged as to attain amarkedly improved and a more eflicient system 5 of waste heat-recoveryfrom an internal combustion engine.

Numerous other objects and advantages of the system will appear from thedescription, and from the drawings wherein:

Fig. 1 is a diagrammatic illustration of one embodiment of theinvention; Fig. 2 is a diagrammatic illustration of a modified system ofthe type shown by Fig. 1, and Fig. 3 is a diagrammatic illustration of afurther modified form of the system.

Referring now to the drawings, and more particularly to Fig. 1 thereofwhich illustrates one form of the invention, 5 designates generally, aninternal combustion engine preferably of Diesel type. The engine may beused to drive any desired apparatus requiring motive power, or may becoupled to an electric generator (not shown) for supplying electricpower. The engine structure includes a fluid jacket through which iscirculated a cooling fluid, preferably soft water.

The circulating system for the jacket includes a storage receiver or hotwell 6, a delivery conduit i connecting the well to the engine jacketthrough a pump 8 which may be'driven from the engine, and a returnconduit 8 connecting the jacket out- 5 let with the hot well. A hot welloverflow connection I0 is provided fora purposelater appearing, theoverflow serving also, to maintain substantially atmospheric pressurewithin the hot well. Make-up water for the, jacket cooling sys- 1o temis obtained through a conduit l2 connecting the hot well with a sourceof soft water (not shown). Delivery of make-up water to the hot well iscontrolled by a valve ii in conduit l2, the valve being automaticalyoperated by a thermo- 15 static device 114 which in the present example,is preferably of well known Sylphon type, having. its temperatureresponsive element I5 extended into the lower portion of the hot well,as shown. Thus, the thermostat functions to control the 0 valve l3responsive to temperature conditions of the cooling fluid. The jacketwater cooling system which, as will be observed, is of the closedcirculatory type, includes a heat exchanger l6 having a coil lGa thereinarranged in circuit with 25 the return, conduit 9. The cooling waterpassing through the engine jacket, enters the return conduit 9, say forexample, at about 180 degrees F., and then flows through the coil Na inthe heat exchanger l6 wherein it is cooled to about 30 degrees F. bycold service water circulated through the heat exchanger, as will belater described. Thus the cooling water is returned to the hot well atabout 170 degrees F., during normal operation of the system. As a meansfor 35 maintaining the temperature of the water in the well, and hencethat of the water delivered to the engine jacket, below a predeterminedvalue, say 172 degrees F., the thermostat II is regulated so that itwill operate to open valve l3 when the temperature of the water in thehot well exceeds the limit of 1'72 degrees F. i This permits cold waterto flow from the make-up, supply to the hot well, thus cooling the watertherein so as to reduce the temperature thereof below the 1'12 degreelimit. The flow of cold, make-up water to the well may continue untilthe temperature of the water in the well has been reduced to or belowthe set limit, at which time the thermostat will operate to close valveit. Also. an extended inflow of make-up water will fill the hot well,the exces water flowing out through the overflow III. In this manner,the temperature of the water entering the engine jacket is controlledand maintained below the predetermined maximum, and u constant value,v180 degrees F. in the present example, the temperature of the coolingwaterleaving the engine jacket; In any event, it is to be understoodthat the limitoi' 172 degrees herein noted, is determined, say forwinter operation of the engine, and that during summeror other seasonaloperation ofs'the engine, the temperature limit may be set at some othervalue. It is to be noted also, that the inlet and outlet temperatures ofthe cooling water circulated through the engine jackets, will varyaccording to the type of engine 'used, its installation in high or lowaltitudes, and other factors which need not behere enumerated. Hence,the herein noted inlet 1 and outlet temperatures of 170 degrees and 180degrees respectively, are given by way of example only. Y

The hot service water system which is by preference a closed circuit inthe example of Fig. 1, includes a hot water storage tank or receiver l1.Connected to the bottom of the tank is a conduit I9 which extends to theintake of a circulation pump 20. A conduit 2| extends from the pumpdischarge outlet to the heat-exchanger [6, and from the exchanger aconduit 22 extends to an exhaust heat-exchanger 23 functionallyassociated with an exhaust discharge conduit 24 for the engine 5. Theoutlet of heat-exchanger 23 is, in turn, connected with the receiver I!by a conduit 25, the end portion 26 of this conduit which enters thetank l1 being extended to a point substantially near the bottom of thetank, as shown in Fig. 1. Hot water is drawn from the tank forconsumption, through an outlet pipe 21. Cold water is supplied to thehot water system from a suitable source of supply, such as a city watermain (not shown), through a pipe 28- which is connected to the conduitl9 as by a T- connection 23. The pressure of the water in the city mainmay vary in diii'erent localities, but in the present example, thispressure may be assumed as about 60 pounds. Located in conduit I9between the tank and the T-connection 29, is a one-way or check valve 30permitting flow or water from the tank through conduit l9 to of thesystem, a direct flow of water from the supply into the tank.

From the foregoing, it will be observed that the circulation of water inthe hot-watersystem, as maintained by the pump 20, is as shown by thearrows (Fig. 1), from the tank I! through conduit l9, pump 20, enginejacket water heatexchanger l6, conduit 22, exhaust heat-exchanger :3,and thence back to thextank n through the return conduit 25. The waterthus circulated, is heated in each of the heat-exchangers l6 and 23, andthereby provides a supply of hot water in tank I'L,

In the operation if the system, when the engine is running and no wateris drawn from tank H, the water in the service system circulates in theclosed circuit above described. Moreover, as long as the tank issubstantially full, there will be no inflow to the system, of cold,make-up water from the city main through pipe 28, as the pressure in thesystem attains a value approximately equal to the city main pressure of60 pounds, this being suiiicient to prevent such inflow. In the may evenapproach the boiling point, if-no with drawal of water from the tank I]occurs during a relatively long period of time. Accordingly, as a meansfor preventing undesirably high temperatures of the service water, thetank ll may be provided with an overflowconnection 3| extending from theupper portion of the tank, the connection including a valve 33, whichduring normal operation of'the system, remains closed.

Valve 33 operates automatically, by a thermostatic device 34 which issuitably associated with the return pipe or conduit 25 so as to beresponsive to the temperature of the water in such pipe. The thermostatmay be of Sylphon type, and is regulated to efieet an opening of valve33 when the temperature of the service water in pipe 25 exceeds apredetermined value, say 162 degrees F. Opening of valve 33 tends toreduce the pressure in the tank I! and hence in the circulating system,so that cold water may enter thesystem from the city main. Addition ofcold water tends to increase the volume of water circulating in thesystem, so that hot water in excess of the capacity of tank I 1 will bedischarged through the overfiow connection 3| Thus the inflow of coldwater in the temperature of the service water to or below 162 degreesF., whereupon the thermostat 34 will operate to close valve 33.

Withdrawal of water from the tank to consumption through the outlet pipe21, reduces the pressure and volume of the water circulating in thesystem, the pressure drop permitting an inflow of cold water from thesupply or city main in an amount equivalent to the service withdrawal.In this manner, the pressure and volume of water circulating in thesystem may be maintained substantially constant under all operatingconditions. It is to be noted, however, that the .temperature of theservice water may vary under different conditions of engine operationand service demand for hot water, but in any event, the maximumtemperature of the service water is limited to a predetermined value, as162 degrees F. in the present example.

Fromthe foregoing, it will be observed that the service water, whilepassing through the heatexchanger l6, absorbs heat supplied from theengine jacket water. It is understood, of course, i

the: service water. Also, as described, the maximum temperature of thewater in the engine jacket system and that in the service system, areautomatically controlled and limited to suit the respective requirementof each system. It may be noted in this connection that since theservice water temperature is limited to a maximum of 162 degrees F., thethermostat l4 controlling the valve l3 in the jacket water system may beomitted, provided the heat-exchange capacity of the jacket waterheat-exchanger system 16 is such as to cool the jacket water to or below172 degrees F., when the engine It is operating at maximum capacity andunder a sustained load.

- However, to assure a positive maximum temperature control 0! thejacket water in the hot well ,it is preferred to utilize the thermostatl4 in the manner described. a

In the event 01' a service demand for a continuous flower hot water overan extended period of time, the'normal thermal-exchange capacity of theheat-exchangers l6 and 23 may be exceeded, so that the temperature ofthe water delivered to the tank I! and flowing to consumption may bereduced considerably below the maximum limit of 162 degrees F. But thecapac-v ities of the storage tank and the heat exchangers,

together with the circulating capacity of pump 20, may be predeterminedfor a given installation of the system, so that in the event of such asustained demand for hot water, the temperature thereof will not dropappreciably below say about degrees F.

In Fig. 2 is illustrated, diagrammatically, a

modified system of the type shown by Figure 1,

thesystem being applied to a plurality'of internal combustionvengines35. Three such engines preferably of Diesel type, are shown in thepresent example, although any suitable number may be used, dependingupon the power requirements of the particular installation. The enginesare cooled by a jacket cooling system of a closed-circuit type, thecircuit including an expansion tank 36 for make-up water and a conduitor header pipe 31 extending from the tank to engine-driven pumps 38associated with the jacket spaces of the engines 35. A pipe 40 isconnected to the jacket outlet of each engine and to an outlet header 4|in the manner shown, the header 4| being extended for connection to theheader 31. Associated with header 4| and in circuit therewithisa'heat-exchanger 42, provided for a purpose presently to appear. It willbe observed that the engine jackets and pumps are connected in parallel,between the headers 31 and 4|, and that the jacket cooling water iscirculated by the pumps in a closed circuit including the heat-exchanger4!. The heat-exchanger 42 which may be similar to the heatexchanger I8shown in Fig. 1, serves to heat service water circulated in a servicewater circuit now to be described, and in so doing, to cool the enginejacket water. 1

Cold service water from a suitable supply. such it is circulated inthermal relation to the jacket water flowing therethrough. The servicewater passing through the heat-exchanger, flows through a header 44 toindividual exhaust heatexchangers 45, one being thermally associatedwith the exhaust conduit 41 of each engine. A header 48 connects theservice water outlet oi each exhaust heat-exchanger and conducts theservice water therefrom to a hot water storage tank or receiver 49. Fromthe tank, the hot service water is conducted to consumption through aconduit 50. A forced circulation of the service water in the system maybe maintained by a suitable pump 5|, the inlet of which is connected tothe tank outlet pipe 50 through pipe 52, and the pump outlet ordischarge connected as by pipe 53, to the header 44, preferably adjacentthe heat-exchanger 42. Thus a closed service water circulation system isattained, the

closed circuit including the tank 49, pump 5| and' substantially filledat all times during normal operation of the system, and this conditionis maintained even though frequent service demands for hot water aremade upon lieltank 48. When there is no withdrawal 0! hot water 5 toservice consumption, the pump 5! circulates the water in the closedsystem described, and during this time, there is substantially no inflowfrom the source or cold, makeup water, as the pressure inthe closedvsystem about equals the 10 pressure of the source. However, in the eventof a service withdrawal from tank 49, the pres-- sure in the system isreduced, thus permitting a flow of cold water through heat-exchanger 42and into the circulating system, in an amount equiv- 15 alent to thevolume of hot water withdrawn.

In those instances where there may be little or no service withdrawal ofhot water from tank 49, the service water circulated by the pump 5|through the tank and the several-exhaust heatexchangers 45, may becomeheated to an undesirably high temperature. Moreover, should the enginesbe operating under sustained, heavy loads, the heating of the servicewater by the exhaust heat-exchangers may be suihcient to cause the waterto boil. Accordingly, it is most desirable to limit the. maximumtemperature of the service water to a reasonable value.

In attaining this end, there is provided a wastedischarge pipe 54 whichis connected to the header 48 at a point near the connection of theheader to the storage tank 49. A control valve 55 is associated with thedischarge pipe 54, the operation of the valve being effectedautomatically by a thermostatic device 56 which is functionallyassociated with the header. 48 so as to operate in responseto thetemperature of the service water in the header. The valve and thermostatarrangement may be of Sylphon type, with the thermostat regulated sothat it will effect an opening of the valve when the service watertemperature exceeds, say degrees F. Opening of valve 55 permits adischarge'of service water to waste, through pipe 54, and this in turn.results in an inflow .to the service system, of water from the citymain, as through pipe 43. The resultant flow of fresh water through thesystem to waste discharge, effects a reduction in the temperature of theservice water to or below the maximum limit of 170 degrees F. When thetemperature of the service water falls below the maximum setting ofthermostat 56, the thermostat eflects a closure of valve 55 to restorethe system to normal condition.

The temperature of the cooling water entering the engine jackets iscontrolled so that it will not exceed a predetermined maximum of say1'70 degrees F., the selection of the limiting temperature beingdetermined at one value for operation of the engine during cold orwinter months, and 50 at another value during the hot or' summer months,as heretofore pointed out. A maximum temperature limitation of the waterentering the engine jackets, tends to limit the maximum temperature ofthe water leaving the engine jackets, 5 under conditions of normalengine operation. Of course, greater loading of the engine will tend toincrease the jacket. exit temperature of the water, due to the greaterheating of the engine parts during operation under heavy loading.However, for the purpose of the present example, with the temperature ofthe ,water delivered to the engine jackets limited to 1'70 degrees F.,the outlet temperature of the jacket water may be about degrees F. Thusit is to be notedthat exceed 170 degrees F.

A pipe or conduit 51 is connected to the service water-pipe or header44, between the jacket water heat-exchanger 42 and the exhaustheatexchangers 45. This pipe leads to a suitable point ofwaste-discharge, so that under certain conditions, water from the citymain may flow through the heat-exchanger 2 and thence through pipe 51 towaste. A valve 58 is included in the pipe 51, and is automaticallycontrolled by a thermostatic'devicei! which is functionally associatedwith the jacket water header 4! so as to be responsive to the jacketoutlet temperature of the engine cooling water. The thermostatic device59 is preferably of Sylphon type,

operating directly upon the valve 58 in a man-.

ner to open the valve when the temperature of the jacket water in headerll exceeds the desired limit of say 180 degrees F. Opening of valve 58permits a flow of service water from the city main through pipe 43,heat-exchanger 42,, header l4 and 'pipeil to discharge. The increasedflow of cold service water through the jacket water heat-exchanger"effectively cools the jacket water, so as, to reduce the temperature ofthe water entering the engine jackets to or below the desired maximumlimit of 1'70 degrees F. It

is to be noted that a flow of cold water through heat-exchanger 42 andthence to waste through pipe 51in response to opening of valve 58, may

occur independently of a flow of the service water from heater 2 to theservice water system inresponse to the opening of waste discharge valve55 or to a withdrawal of hot service water from tank 48 to consumption,and vice versa.

The operation of the modified system as illustrated by Fig. 2, isbelieved tobe evident from the foregoing description. However, it isdesired to point out that like the system of Fig; 1, the service watersystem of Fig. 2 is substantially a constant volume, but variabletemperature arrangement, which presents many advantages evident to thoseskilled in the art to which this invention pertains.

Fig. 3 illustrates diagrammatically, a further embodiment of theinvention, relating to a substantially constant temperature, variablevolume service water heating arrangement associated with an internalcombustion engine 60. Engine 60 is preferably of Diesel type, and iscooled by a closed-circuit jacket system which includes a heat-exchanger6|. The heat-exchanger is in circuit with the engine jacket spacethrough a pipe 62 connected. to the jacket outlet, and a return pipe 63connected to the jacket inlet through a circulation pump 64. The pump 64in the present example, is preferably driven by the engine 60 in anysuitable manner. sion tank 65 is connected tothe return pipe 63 througha pipe 61, the tank serving also, as a limited source of make-up waterfor the jacket cooling system. Tank 65 is arranged so as to provide onlya slight pressure head for the cooling water circulating in'the jacketsystem, the low pressure in the system serving to minimize leakage atthe pipe joints, as well as internally f tank 16 to points of hot watershown).

An expanheat-exchanger, wherein it circulates in thermal relationto thejacket cooling water also circulated therein. From the heat-exchanger8|, the heated service water is conducted by pipe II to a secondheat-exchanger 12 which is functionally associated with the engineexhaust discharge duct H, the water being furtherheated therein andthence conducted by a pipe 15 to the lower or bottom end of a storagereceiver or stand-pipe 16. A pipe 11 extends from the bottom portion ofconsumption (not The hot service water collecting in tank 16 is bypreference, maintained under a substantially uniform pressure which maybe about equal to the pressure under which the hot water. is deliveredto the tank by the action of the pump 89. In the present example, awater pressure of 60 pounds may be assumed, and this pressure may bemaintained in the tank 16 by supplying to the upper portion thereof, airunder a pressure of about 60 pounds. For this purpose, a suitable.motor-driven, air compressor unit 18 may be utilized to delivercompressed air at 60 pounds pressure, to the tank through a pipe 19. The

compressor unit may be automatically controlledv in any well knownmanner, so that it will operate to delivercompressed air when thepressure in the tank '16 falls to say about 57 pounds, and will ceasedelivering compressed air when the tank pressure is about 60 pounds. Anoverflow pipe ll including an automatically operating safety valve 82,is connected to the upper por-- tion of the tank, provision thereofbeing made so that in the event the pressure in the tank materiallyexceeds 60 pounds, the valve 82 will open to vent water and air from thetank. whereby to relieve the excess pressure.

Between the inlet and outlet pump 69 is a by-pass connection 83 whichincludes an automatic, pressure-operated valve 84. Valve 84 opens whenthe pressure in tank 16 is about 60 pounds and the pump is attempting toeffect a delivery of servicewater thereto, against such pressure. Inthis case, the pump will circulate service water about the lay-pass,with substantially no delivery to the tank. However, when service wateris withdrawn from the tank to consumption, thereby reducing the tankpressure below 60 pounds, the by-pass valve 84 will close so that pumpter to the tank. In the present example, valve 84 may be regulatedtoclose when the backpressure thereon drops to about 57 pounds.

Under the conditions of no withdrawal of hot water from tank 16 toconsumption, and a pressure of about 60 pounds in the tank, servicewater from the citymain will be circulated by pump 69 about by-pass 83.Hence there will be no flow of service water through the heat-exchangeril. If this condition obtains for an appreciable time, the engine Jacketwater may heat 69 may deliver make-up waup to an undesirable degree.Accordinglythe spears:

maximum temperature of the jacket water is limited in a manner now to bedescribed.

Suitably associated with the jacket outlet pipe 62 is a thermostaticdevice 85 which is preferably of Sylphon type. The thermostat isresponsive to the temperature of the jacket water leaving the enginejacket, and is arranged to operate a valve 86 controllingwaste-discharge of hot water from tank It, as through a pipe 8!connected to the tank. In the present example, say it is desired tolimit the maximum temperature of the jacket water issuing from theengine jackets, to-about 1'10 degrees F. and in so doing, to limit themaximum temperature of the cooling water entering the engine jackets toa desired value below l'lgldegrees, say 160 degrees F. Accordingly, theermostat 85 is regulated to efl'ect an opening of valve 86 and therebyto vent hot water from tank I6, when the outlet temperature of thejacket water exceeds 1'70 degrees F. Venting of the water from tank I6reduces the pressure therein, so that the pump by-pass valve 84 willclose to permit the pump 69 to deliver make-up water to the tank. Thus apositive flow of service water through the heat-exchanger 6| willresult. Hence, the jacket water will be cooled in its passage throughthe heat-exchanger, to restore the jacket inlet and outlet temperaturesto or below the predetermined limits above noted. Upon the restorationof the water temperatures in the jacket cooling system,

thermostat 84 will efiect a closure of venting valve 86. It is to benoted that the above described operation of the thermostat and ventingexpedient, is independentof service water withdrawal from the tank 16,the described control being particularly advantageous when there is noservice demand upon the tank 16 for extended periods of time. It is tobe understood from the foregoing, of course, that when relativelyfrequent service withdrawal of water from tank 16 occurs, there will bea correspondingly frequent flow of cold service water through the jacketwater heat-exchanger 6|, and thisunder normal operation of the system,will, be sufllcient to maintain the jacket water below the predeterminedmaximum temperature limits.

Since the service water pump 69 is driven by the engine 60,-so' thatthe'rate of water .dis: placement thereby is substantially proportionalto engine speed and hence engine-loading, the heat-exchange rate of theexchanger II will be substantially constant under normal operatingconditions. For the same reason, the thermal exchange rate of theexhaust heat-exchanger 12 under normal conditions, is substantiallyconstant. Hence, it will be observed that the temperature of the waterin tank .16 normally'remains fairly constant. Moreover, the maintenanceof a constant service water temperature in tank 16 is aided by theaction of the thermostatically operated waste-discharge arrangement85-46, serving to limit the maximum temperature of the jacket water.

The several embodiments of the invention herein described fully attainthe foregoing objects, and may be utilized to great advantage, toprovide adequate heat say for normal service water heating required bybuildings, ships and the like, which have installed therein one or moreinternal combustion engines. Further, the systems illustrated areautomatic in operation, and utilize apparatus readily available.

It is to be understood, of course, that while the several embodiments ofthe invention herein described, represent preferred arrangements,alterations or modifications in the elementsand relative dispositionsthereof may be made without departing from, the spirit and scope of theinvention, as defined by the appended claims.

I claim; a

1. In a system of waste heat recovery of the character described, aninternal combustion engine provided with an exhaust discharge conduitand a fluid jacket,a fluid circulating system associated with saidjacket, a heat transfer element-in circuit with said circulating systema second heat transfer element associated with said exhaust conduit, aservice water system includin a source of service water supply, astorage tank and piping connecting said source to the tank through saidheat transfer elements in series, means associated with said servicewater system tending to limit the temperature of the water therein, andthermostatically controlled means adapted for regulating the temperatureof the fluid in said jacket circulating system.

2. In a system of waste heat recovery, the combination of an internalcombustion engine provided with a fluid jacket and an exhaust dischargeconduit, a fluid circulating system in circuit with said jacket, heattransfer elements independently functionally associated with saidcirculating system and said exhaust discharge conduit, a service watersystem associated in heat absorbing relation to said heat transferelements, and means functionally associated with said service watersystem and including a control element therefor, thermally responsive tothe .temperature of the fluid in said jacket circulating system, saidmeans and control element being adapted for regulating the temperatureof the fluid in said jacket circulating system.

said service water system for conducting service water in heat transferrelation to said heat transfer elements in series, and means including athermally responsive element, adapted for controlling the temperature ofthe fluid circulating in said jacket system.

4. In a system of heat recovery in combination with an internalcombustion engine providedwith an exhaust discharge conduit and a waterjacket, a low pressure, water circulating system for said engine jacket,said system including a heat-exchanger, means including a thermostaticelement responsive directly to jacket water temperature, associated withsaid jacket system and adapted for limiting the maximum temperature ofthe water circulated therein, a second heatexchanger functionallyassociated with said discharge conduit, a service water system ofcirculating type including piping in circuit with said heat-exchangers,and means functionally associated with said service water system,tending to limit the temperature of the service water therein.

5. In a system of the type described, an internal combustion engineprovided with a fluid jacket and an exhaust discharge conduit. a fluidcirculating system in circuit with said jacket,

and including a heat transfer element, a heat transfer elementfunctionally, with said exhaust discharge conduit,

second a closed,

service water circulating system thermally associated with said heattransfer elements in service, and independent,thermostatically-controlled means operable for limiting the temperatureof the serviceriwater and the temperature of the fluid circulatedthrough said engine jacket.

6. In a waste heat recovery system in 8880'! ciation with an internalcombustion engine, said engine being provided with an exhaust dischargeconduit and a fluid jacket, afluid circulating system in circuit withsaid jacket, and including a heat transfer element, a second heattransfer element functionally associated with said discharge conduit, aclosed service water circulating system including a storage tank inseries circuit relationto said second heat transfer element, a source ofservice water supply, means for conducting water fromsaid source throughsaid first heat transfer element and to said closed service watersystem, a service water "by-pass connection between first heat transferelement and said service water system, and means thermally responsive tojacket fluid temperature, for controlling saidby-pass connection.

7. A system of waste heat recovery in association with a plurality ofinternal combustion engines, each provided with an exhaust dischargeconduit and afluld jacket, a closed fluid circulating system 'forsaidengine jackets, said system including a heat transfer element, heattransfer elements associated with said discharge 5 conduits, a servicewater circulating system in circuit with said exhaust conduit heattransfer elements, a source of service water supply, means forconducting service water from said source through said first heattransfer element and to 11 said service water system, and meansfunctionally associated with said service water system, adapted forlimiting the maximum temperature of the service'water circulatedtherein.

8. In a heat recovery system of the type described, a plurality ofinternal combustion engines, each having an exhaust discharge conduitand fluid jacket, fluid circulating means in circuit with said enginejackets and including a heat transfer element, a heat transfer elementassociated with each of said exhaust discharge conduits, a service watersystem in circuit with said heat transfer elements, and means in said 7associated I .ment, a second heat transfer element by-pass therefor,

'of water from the tank system, adapted for limiting the ,maximumtemperature of the fluid circulated in said jacket system and of theservice water in system. r

9, In asystemof waste heat recovery, in association with an internalcombustion engine having an exhaust discharge conduit and a fluidjacket, a fluid circulating system in circuit with said jacket andincluding a heat transfer elefunctionally assoclated with said exhaustdischarge conduit, and a service water system including in series, saidheat transfer-elements and a storage said service tank, a service watercirculating pump and a tain a predetermined water pressure in saidservice storage tank.

10. In a system of internal combustion a fluid circulating waste heatrecovery, an engine ha i a fluid jacket, system in circuit with saidjacket and including a heat-exchanger, a service water system includingin series, a storage tank and said heat-exchanger, a discharge outletfor said tank, and means responsive to temperature conditions of thefluid circulated through said engine jacket, adapted for controllingdischarge through said outlet.

11. In a waste heat recovery system of the character described, aninternal combustion engine of jacketed water-cooled type Provided withan exhaust discharge conduit, a closed cooling water system associatedwith the engine jacket, a heat transfer element functionally associatedwith said jacket system, a second heat transfer element functionally.associated with said exhaust conduit, a eluding means for conductingservice water in heat exchange relation to said heat transfer elements,and means including a thermally operated element responsive totemperatures of the water in said jacket cooling system, adapted forvarying the rate of conduction of service water in heat transferrelation to the first said heat transfer element, whereby to control thetemperature of the water in said jacket cooling system.

FRITZ PAUL GRUTZNER.

I said by-pass comprising a fluid, connection including a unidirectionalvalve, ar-

service water system in-.

